The present invention relates to network communications, in particular to network systems for which a network node maintains more than one connection with another network node.
Port aggregation (also called link aggregation, teaming or trunking) is a method by which two or more network connections are grouped together at a multiport network host to create a single logical connection. One purpose of this grouping is to be able to increase bandwidth for that single logical connection without having to increase the bandwidth of any of the physical network channels. For example, full-duplex Ethernet or Fast-Ethernet connections can be grouped in this fashion to avoid or delay upgrading a network infrastructure to Gigabit Ethernet or asynchronous transfer mode (ATM).
Typically associated with port aggregation is a port fail-over method that ensures that the logical connection is maintained in the event that an individual network link or network interface card (NIC) fails. Such a port fail-over method can also provide increased reliability for that single logical network connection, in comparison with the reliability of a single physical network connection.
To provide an increased number of connections for a network host, the host may be connected to plural networks with plural NICs. A port aggregated logical connection may in this case involve plural ports of the plural NICs. The use of plural NICs may, however, strain a host central processing unit (CPU) due to the additional network protocol processing required for the additional NICs.
Even without additional NICs, protocol processing may absorb a large fraction of host CPU cycles. This is because conventionally, data such as a file that is transferred over a network is divided into multiple packets, with each packet having layers of protocol headers that are processed one layer at a time by the CPU of the receiving host computer. Although the speed of CPUs has greatly increased over many years, host protocol processing of network messages such as file transfers can consume most of the available processing power of the fastest commercially available CPU.